Technical overview

General premise

Telpin uses both the untyped and the typed syntax tree to construct a signature file.
It will traverse over all the nodes of the untyped tree and, where applicable, construct the signature counter parts.

For example a SynBinding becomes a SynValSig.
The signature AST is really constructed as close as possible to the implementation AST.
You'd be surprised how many information can just be re-used going from implementation to signature AST.

When the untyped tree does not contain sufficient information, a FSharpSymbol will be queried from the typed tree to enrich the missing information.

Solution structure

graph TD D[Teplin.Core] E[Telplin] F[Telplin.Lambda] G[Telplin.Core.Tests] D --> E D --> F D --> G H[Telplin.Deploy] I[OnlineTool]

Telplin.Core

Has a reference to Fantomas.Core and processes the untyped tree using the Oak model. Note that Fantomas does not use FSharp.Compiler.Service.

Also references the FSharp.Compiler.Service and is being used to type check the implementation file.
The untyped tree constructed by the FSharpChecker is very deliberately not used, due to its incompatibility with Fantomas.

Telplin

A command line tool application that reads a MSBuild binlog file and can generate signatures.
The main reason to use a binlog file, is that Telplin needs the compiler options to get the typed tree.
Another benefit would be the insurance that all referenced projects are built and available.